Genuine Unistrut P1000T 1-5/8" 12 Gauge Strut Channel, Slotted Back, Pre-Galvanized 5 Foot Length Genuine UNISTRUT Brand 1-5/8" x 1-5/8" Square 12 Gage Steel Strut Channel 9/16" x 1-1/8" Short Slotted Back Channel Silver Finish: Pre-Galvanized Zinc; ASTM A653